Q. For a redox reaction, if the standard reduction potentials are E°(A/B) = 0.80 V and E°(C/D) = 0.40 V, which species is the stronger oxidizing agent?
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Solution
The stronger oxidizing agent is the one with the higher reduction potential. Here, A/B has a higher E° than C/D.
Correct Answer:
A
— A
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Q. If the concentration of reactants in a redox reaction is doubled, how does it affect the cell potential according to the Nernst equation?
A.
Increases
B.
Decreases
C.
Remains the same
D.
Depends on temperature
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Solution
Doubling the concentration of reactants increases Q, which decreases E according to the Nernst equation.
Correct Answer:
B
— Decreases
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Q. In a concentration cell, if the concentration of the anode is 0.1 M and the cathode is 1.0 M, what is the cell potential at 25°C?
A.
0.059 V
B.
0.118 V
C.
0.059 log(10)
D.
0.118 log(10)
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Solution
E = (0.059 V/n) * log([Cathode]/[Anode]) = (0.059 V/2) * log(10) = 0.059 V.
Correct Answer:
B
— 0.118 V
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Q. In a concentration cell, if the concentration of the anode is 0.1 M and the cathode is 1 M, what is the cell potential at 25°C?
A.
0.059 V
B.
0.118 V
C.
0.059 log(10)
D.
0.118 log(10)
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Solution
E = (0.059 V/n) * log([Cathode]/[Anode]) = (0.059 V/2) * log(1/0.1) = 0.059 V * 1 = 0.059 V.
Correct Answer:
B
— 0.118 V
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Q. In a Daniell cell, what is the role of the salt bridge?
A.
To provide a pathway for electrons
B.
To maintain charge neutrality
C.
To increase the cell potential
D.
To facilitate ion exchange
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Solution
The salt bridge maintains charge neutrality by allowing ions to flow between the two half-cells.
Correct Answer:
B
— To maintain charge neutrality
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Q. In a Daniell cell, which species is reduced?
A.
Zn
B.
Cu²⁺
C.
Zn²⁺
D.
Cu
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Solution
In a Daniell cell, Cu²⁺ is reduced to Cu at the cathode.
Correct Answer:
B
— Cu²⁺
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Q. In a galvanic cell, if the anode reaction is Zn → Zn²⁺ + 2e⁻, what is the half-reaction at the cathode if Cu²⁺ is reduced?
A.
Cu + 2e⁻ → Cu²⁺
B.
Cu²⁺ + 2e⁻ → Cu
C.
Cu²⁺ → Cu + 2e⁻
D.
Cu → Cu²⁺ + 2e⁻
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Solution
The cathode reaction involves the reduction of Cu²⁺ to Cu: Cu²⁺ + 2e⁻ → Cu.
Correct Answer:
B
— Cu²⁺ + 2e⁻ → Cu
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Q. In a redox reaction, if the oxidation state of manganese changes from +7 to +2, how many electrons are gained?
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Solution
The change from +7 to +2 indicates a gain of 5 electrons (7 - 2 = 5).
Correct Answer:
C
— 2
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Q. What is the effect of increasing temperature on the cell potential of an electrochemical reaction?
A.
Increases cell potential.
B.
Decreases cell potential.
C.
No effect on cell potential.
D.
Depends on the reaction.
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Solution
The effect of temperature on cell potential depends on the reaction's enthalpy and entropy changes.
Correct Answer:
D
— Depends on the reaction.
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Q. What is the effect of increasing temperature on the cell potential of an electrochemical cell?
A.
Increases cell potential
B.
Decreases cell potential
C.
No effect
D.
Depends on the reaction
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Solution
The effect of temperature on cell potential depends on the reaction's enthalpy and entropy changes.
Correct Answer:
D
— Depends on the reaction
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Q. What is the Nernst equation used for calculating the cell potential under non-standard conditions?
A.
E = E° - (RT/nF)ln(Q)
B.
E = E° + (RT/nF)ln(Q)
C.
E = E° - (nF/RT)ln(Q)
D.
E = E° + (nF/RT)ln(Q)
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Solution
The Nernst equation is E = E° - (RT/nF)ln(Q), where R is the gas constant, T is temperature, n is moles of electrons, and F is Faraday's constant.
Correct Answer:
A
— E = E° - (RT/nF)ln(Q)
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Q. What is the relationship between Gibbs free energy (ΔG) and cell potential (E) in an electrochemical cell?
A.
ΔG = -nFE
B.
ΔG = nFE
C.
ΔG = -E/nF
D.
ΔG = E/nF
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Solution
The relationship is given by ΔG = -nFE, where n is the number of moles of electrons and F is Faraday's constant.
Correct Answer:
A
— ΔG = -nFE
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Q. What is the relationship between Gibbs free energy change (ΔG) and cell potential (E) in electrochemistry?
A.
ΔG = -nFE
B.
ΔG = nFE
C.
ΔG = -E/nF
D.
ΔG = E/nF
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Solution
The relationship is given by ΔG = -nFE, where n is the number of moles of electrons and F is Faraday's constant.
Correct Answer:
A
— ΔG = -nFE
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Q. What is the standard cell potential (E°) for a galvanic cell composed of a zinc electrode and a copper electrode?
A.
0.34 V
B.
1.10 V
C.
0.76 V
D.
1.96 V
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Solution
E° = E°(Cu²⁺/Cu) - E°(Zn²⁺/Zn) = 0.34 V - (-0.76 V) = 1.10 V.
Correct Answer:
B
— 1.10 V
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Q. What is the standard electrode potential for the reduction of Ag⁺ to Ag?
A.
0.80 V
B.
0.46 V
C.
0.34 V
D.
0.00 V
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Solution
The standard electrode potential for the reduction of Ag⁺ to Ag is 0.80 V.
Correct Answer:
B
— 0.46 V
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